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Conservation Dairy Farming

In the study, the conservation dairy-farming systems — which have been developed and tested by Penn State researchers over the last decade — produce the majority of the feed and forage crops consumed by their cattle, use no-till planting, have continuous diversified plant cover, and one system employs manure injection. Image: Karsten Research Group / Penn State

Researchers modeled nutrient and sediment loading to compare nonpoint pollution from “typical” and “conservation” farms, simulating effects for dairy farms in a small drainage in central Pennsylvania. In the simulations, the conservation farms produce most of the cattle’s feed and forage, use no-till planting, and have continuous diverse plant cover, and one scenario includes manure injection.

Compared to the typical Pennsylvania dairy farm, the enhanced conservation dairy-cropping scenarios improved water quality. Over the 12-year simulation, they cut the number of in-stream peaks of nutrients and sediment and reduced average concentration of sediment by 31 percent, organic nitrogen by 41 to 53 percent, nitrate by 23 percent, organic phosphorus by 36 to 45 percent, and soluble phosphorus by 32 to 43 percent. Both conservation scenarios also decreased nitrous oxide emissions by reducing denitrification, but the scenario that included manure injection retarded 91 percent of nitrogen volatilization that occurred with broadcast manure.

If most dairy farms in Pennsylvania fully adopt conservation best management practices, the state may be able to achieve its total maximum daily load water-quality target for the Chesapeake Bay. But achieving large-scale adoption of conservation dairy farm practices will not be easy or cheap. Farmers will need access to affordable land to grow more feed and apply manure at lower rates, as well as technical assistance and financial incentives.